THE SIMULATION OF 42-VOLT HYBRID ELECTRIC VEHICLES

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					              THE SIMULATION OF
               42-VOLT HYBRID
              ELECTRIC VEHICLES
                                                     by
                                          Andrew Campbell
                                         Aishwarya Rengan
                                             Jakob Steffey
                                       with the assistance of:
                                          Joshua Ormiston


        Abstract: The objective of this project involves the selection and modification
of a hybrid electric vehicle (HEV) simulator in order to find the best possible
combination of engine and motor size in a sport utility vehicle. This combination will
increase fuel efficiency and lower harmful emissions. After investigating HEV
simulators, ADVISOR was chosen, the National Renewable Energy Laboratory’s hybrid
electric vehicle simulator. This paper outlines the way ADVISOR models vehicles, what
changes are necessary in order to model a 42-volt battery system, and the simulations
done in order to maximize performance. The results show that in order to meet daily
driving demands, a 140 kW engine, coupled with a 15kW motor is the preferred
combination that will maximize fuel efficiency and reduce emissions.




Work done for McCleer Power Incorporated, under the direction of Dr. Pat McCleer, in partial fulfillment of
the requirements of Michigan State University MTH 844/890/490, advised by Professor Ronald Rosenberg
                                                    Table of Contents


Nomenclature ...................................................................................................................... 3
1. Introduction ................................................................................................................. 4
2. Hybrid Electric Vehicle Simulators ............................................................................ 5
3. A more detailed description of ADVISOR ................................................................. 6
4. Modifications of ADVISOR ....................................................................................... 9
5. Simulation Procedure ................................................................................................ 11
6. Results and Discussion.............................................................................................. 12
7. Conclusions ............................................................................................................... 16
8. Limitations of this Study........................................................................................... 17
REFERENCES.................................................................................................................. 18
Appendix A. Sample MATLAB® Code (mc file) ............................................................. 19
Appendix B. Important ADVISOR Modules.................................................................... 24
Appendix C. Forward and Backward-Facing Simulation Diagrams................................. 30
Appendix D. ADVISOR Output – Incorrectly Modified Motor File................................ 32
Appendix E. Raw Data and Calculations .......................................................................... 34




                                                                 2
                          Nomenclature

Name       Definition
Ah         amp hour capacity
Ahcap      maximum amp hour capacity
Ahused     amp hours used
EC         watt-hour energy capacity
eff        motor efficiency
I          current from battery
Pbty       required battery power
Pbus_a     available power to the power bus
Pmax       maximum energy storing system discharge
Pmotor     power required from motor
Ptotal     total power used by motor
Pwire      power loss from wires
Rbty       internal resistance of single battery
Rintpack   resistance of battery
Rbty_new   new internal resistance of each battery
Rset       internal resistance of the set of batteries
Rtot       total internal resistance
Voc        open circuit battery voltage
Vocbatt    single battery open circuit current
Vbus_a     available voltage to the power bus
ω          angular velocity of motor
τ          torque required from motor
τc         torque required for charging battery
τint       torque needed to overcome motor inertia
τsum       total torque required from engine
τT         tractive torque




                                 3
1.      Introduction
Electric vehicles have existed in one form or another since the late 19th century. In 1898
the German automaker Dr. Ferdinand Porsche built his first car. It ran on electric power.
These cars were always limited by the battery’s available energy supply, but in the early
days of automobiles, their range per battery pack charge was competitive with the
distance a gasoline-powered car could travel on one tank of gas. As rapid improvements
in internal combustion engines were made, the electric car lost its market share to the
gasoline automobile. The electric car was never completely forgotten. Electric vehicles
made intermittent reappearances in America, especially as the result of the oil embargo in
the 1970’s, and consumer demand for better fuel economy [1].
        When emission regulations tightened in the last quarter of the 20th century and
engineers made breakthroughs in hybrid and electric vehicle technology, automobile
manufacturers began to look more seriously into vehicles with alternative power sources.
With current battery technology, electric vehicles are still severely limited by their range
per battery pack charge. Since electric motors yield quick acceleration and internal
combustion engines excel at steady speed operation, hybrid electric vehicle (HEV)
technology allows the car to draw upon the benefits from both devices.
        HEVs meet both consumer needs as well as car manufacturer needs. They give
the consumer the ability to use the car for long periods of time without recharging. HEVs
also take a giant step forward in meeting low emission standards set by the Partnership
for a New Generation of Vehicles. HEVs also afford a much higher fuel economy than
that of a conventional vehicle.
        The two configurations of hybrid electric vehicles are the series and the parallel
configurations. In a series configuration, there is no power transferred mechanically
between the gas engine and the wheels. In this type of configuration, power is converted
from chemical, to mechanical, to electrical, and back to mechanical energy. Essentially,
the gas engine powers the generator, which in turn can both charges the battery pack and
deliver power to the motor, and finally the electric motor powers the wheels. The
advantage of a series configuration is that since the engine never idles, there are fewer
emissions, so it is better for the environment. The disadvantage of this configuration
occurs on the highway since the power from engine is converted from mechanical to
electrical and then back to mechanical energy again. The series configuration is less
efficient than the parallel configuration because of the inefficiency in these energy
conversions.
        In the parallel configuration, there is a direct mechanical connection from both the
electric power unit and the gas engine to the wheels. One possible parallel configuration,
the starter/alternator model, has a generator that doubles as an electric motor, coupled to a
gas engine. The batteries power the electric motor and the electric motor powers the
wheels. The gas engine also powers the wheels. In a parallel system, there is also a
possibility of a regenerative braking system — every time the car brakes, the batteries are
charged. The advantage of a parallel configuration is that since both the electric motor
and the engine help in powering the wheels, the car generally has more power than a
series configuration. In addition, at highway speeds, this type of a configuration can
afford a higher fuel efficiency because there are fewer energy conversions than in a series
configuration. The disadvantage of a parallel configuration is that it usually releases
more emissions into the environment than a series vehicle [2].



                                             4
         The two HEVs currently on the market, the Toyota Prius and the Honda Insight,
operate with 274-volt and 144-volt energy storage systems, respectively. There is
increased speculation that the industry standard will change to 42-volt electrical systems.
The change to 42-volt systems will provide more protection against hazardous electric
shock. A 42-volt electrical system will maintain a level of safety that today’s HEVs
cannot. Even conventional vehicles are moving in the direction of a 42-volt electrical
system in order to power the growing number of amenities in luxury vehicles and
possibly to introduce electrically actuated valves, electric water and oil pumps, and even
electrically heated exhaust catalyst systems. BMW now has prototypes of conventional
vehicles operating on 42-volt systems, and German consumers may be able to purchase
them as early as the 2004 model year. [3]
         SUVs comprised the largest share of automotive sales in the United States in the
2000 model year [4]. Since, today’s typical SUV has a fuel economy of 13 to 16 miles
per gallon (mpg) [5], improvements in the fuel economy of SUVs will have a larger
impact on the world’s gasoline consumption than seemingly larger improvements on
more efficient vehicles. For example, a conventional SUV averaging 15 mpg needs 40
gallons for a 600-mile trip. Improving that by 5 mpg to 20 mpg will save 10 gallons on
the trip. However, if a midsize sedan’s fuel economy is improved by 15 mpg from 25 to
40, the same trip will save only nine gallons of fuel.
         The focus of this project was on modeling a parallel 42-volt starter/alternator
configuration SUV. The main objective was to find the optimum engine and motor size
in order to maximize fuel efficiency and reduce emissions. Another objective involved
the choice of computer simulator to use. In order to model a 42-volt starter/alternator
HEV, the simulation program chosen had to be modified.
         This paper outlines the steps taken to meet the objectives. It discusses the
simulators examined, details the workings of the simulator chosen, describes the
modifications necessary in order to meet the objectives, and finally discusses the data
generated using ADVISOR, an HEV simulation program.

2.      Hybrid Electric Vehicle Simulators
There are many different hybrid electric vehicle simulators available. One of the
objectives of this project was to find the program best suited to allow for the
experimentation with a 42-volt starter/alternator and battery system.
      The first simulator considered was the Idaho National Engineering and
Environmental Laboratory’s SIMPLEV. In SIMPLEV, a driving cycle is the input to the
model. The amount of power needed from the vehicle to complete the driving cycle is
then calculated, incorporating the component efficiencies into the model. SIMPLEV can
predict fuel economy, emissions, and several other variables. SIMPLEV is a DOS based
simulator that limits the user to designing vehicles with preprogrammed components [6].
        The next simulator considered was MARVEL. MARVEL was built to analyze
the performance of a hybrid vehicle that has an internal combustion engine with batteries
for energy storage. It can be used to optimize the size of the battery and internal
combustion engine, based on vehicle-life cycle and cost. This model cannot predict fuel
economy, top speed, maximum acceleration, or several other vehicle performance
parameters.




                                             5
        The third simulator examined was Ohio State University’s OSU-HEVSIM. OSU-
HEVSIM is written in MATLAB®/Simulink® and can predict the fuel economy, top
speed, and max acceleration among other variables. Also, detailed components are easily
changed. This simulator is used in course work at Ohio State University, but the creators
of OSU-HEVSIM suggested using the simulator outlined below. [7]
      The final simulator examined was ADVISOR. It has the ability to simulate parallel
and series HEV's as well as conventional drive trains. It is written in
MATLAB®/Simulink®. It includes a graphical user interface that allows the user to
easily change vehicle parameters between several options without having to modify the
Simulink® block diagrams. Outputs include fuel economy, emissions, and grade
sustainability. ADVISOR was chosen for this project because of the recommendations
received, its ease of use, and because of its widespread acceptance in the automotive
industry. ADVISOR has been used by all of the world’s major auto manufactures [8].

3.     A more detailed description of ADVISOR
ADVISOR operates under the MATLAB® program. When ADVISOR is started, the user
is shown a graphical user interface (GUI) shown in Figure 1 below.




       Figure 1: ADVISOR interface

The user has the ability to define the vehicle simulated. Choices are made from pull
down menus. This GUI provides the choices of drivetrain and components. Figure 1


                                            6
shows a parallel starter/alternator configuration together with SUV characteristics. The
actual calculations used in the simulation are not seen on this GUI.
        ADVISOR runs systems of MATLAB® script files to form its program construct.
ADVISOR has a MATLAB® file for each subsystem in the vehicle (energy storage
system, motor, engine, etc.). Each script file contains the working ranges of variables
necessary to adequately model the performance of the subsystem and working relations
with the subsystems that it is in contact with. An example of this is the motor/controller
(mc) subsystem. The mc script file provides a range of working torque (-305 to 305
N*m), a range of working speeds (0 to 6000 rpm), and the maximum continuous torque
the system can produce over the working speed range. The mc subsystem script is set up
for interpolating the efficiencies of the motor and controller using a two dimensional
matrix correlating the torque and the motor speed. The matrix values correspond to
experimentally measured or estimated data. An example of an mc script can be found in
Appendix A.
        The actual calculations executed by ADVISOR are performed in the Simulink®
program. Simulink® is a graphical programming language for modeling. Simulink®
integrates easily with MATLAB® and is packaged with most versions of MATLAB®. It
uses variables whose values are contained in the MATLAB® script files to perform
calculations necessary to model the vehicle. For example, the actual interpolation
described above is performed in the Simulink® program. Examples of Simulink®
programs are contained in Appendix B along with a detailed discussion of their workings.
        There are two main types of calculations that ADVISOR uses: backward-facing
and forward-facing. In backward-facing calculations, no driver behavior is required.
The user must input the driving pattern, a velocity profile, called the speed trace. The
force required to accelerate the vehicle is calculated and translated into torque. This
procedure is repeated at each stage from the vehicle/road interface through the
transmission, drivetrain, etc., until the fuel use or energy use is calculated. Control
systems like throttle and brake position are not included. In forward-facing calculations,
the user inputs the driver model, then the simulator generates throttle and brake
commands that are changed into engine torque, which is passed to the transmission model
and passed through the drivetrain until a tractive force is computed.
        ADVISOR is a backward/forward-facing vehicle simulator. At its core, it is an
empirical model that uses drivetrain component performances to estimate fuel economy
and emissions. ADVISOR uses both backward and forward-facing calculations in its
simulation. The majority of calculations are done in the backward mode, although in
order to keep the components from exceeding their physical limitations, some forward
calculations are necessary. The backward/forward combination can best be described
with two underlying principles [9]
            • No component will require more power or torque from its upstream
                neighbor than it can use.
            • A component is as efficient in the forward calculations as it was computed
                to be in the backward calculations.




                                            7
ADVISOR’s coupled backward and forward calculations are shown by Figure 2 below.




       Figure 2: Parallel starter/alternator model

Figure 2 shows the top level of ADVISOR’s parallel starter/alternator HEV model,
programmed in the Simulink® environment. Arrows indicate data flow; boxes represent
data processing modules. For example, the box labeled “gearbox” contains all data
processing elements, such as “Sum” and “Product” blocks and look-up tables, necessary
to model the vehicle’s single or multi speed gearbox. Arrows traveling from left to right,
such as the one from the “motor/controller” module to the “power bus” module are part
of the backward-facing model. They pass torque, speed, and power requirement up the
drivetrain. Arrows that loop from right to left are part of the forward-facing model. They
pass available torque, speed, force and power through the drivetrain. Each module
references MATLAB® data that describes the performance of a particular subsystem.
        Most data in an ADVISOR simulation is passed backward. This data in the
Simulink® block diagrams are characterized as “requirements.” Some data is transferred
forward in the Simulink® block diagrams. It is characterized as “available.” Each
module the data is passed to either performs calculations or refers to a loss or efficiency
table. Figures C.1 and C.2 in Appendix C show the separate overall backward and
forward data flow in ADVISOR.
        Before changing the ADVISOR program to simulate a vehicle operating with a
42-volt electrical system, it was necessary to understand the computer language and code
ADVISOR uses in its simulations. As previously discussed, ADVISOR uses the
programming language Simulink® to model vehicles in a forward/backward manner.
This Simulink® code is hidden from the user and a GUI shown in Figure 1 is where the
user defines the vehicle from pull down menus. Simulink® is a graphical programming
language, where code is drawn in block diagram form. The overall Simulink® model for
a parallel configuration starter alternator model is shown in Figure 2. Each of the blocks
in Figure 2 can be further opened to show the graphical code contained within. Detailed
descriptions of the electric assist control strategy module, motor/controller module,
power bus module, and the energy storage system module can be found in Appendix B.
The focus is primarily on the backward calculations in each of the blocks.




                                            8
4.      Modifications of ADVISOR
In order to model a 42-volt configuration of a hybrid electric SUV, modifications had to
be made to some of the subsystems. The subsystems that had to be modified were the
energy storage system (ess) module and the motor/controller module.
        The energy storage system (ess) module models the battery pack as a voltage that
is dependent on the state of charge (SOC) in series with the internal resistance of the
battery. The internal resistance is dependent on the SOC and the direction of the current.
The main input and output of the module is the power required into the bus and the power
available to the bus, respectively. A limit power block is used in the ess module to
prevent the battery pack voltage from dropping below the minimum controller voltage
and the minimum battery pack voltage. This allows the quadratic equation for the current
through the battery pack to be solved. The discharge current equation is

                                Rint pack I 2 − VocI + Pbty = 0 ,                                (1)

where Rintpack is the resistance of the battery, I is the current from the battery, Voc is the
open circuit battery voltage, and Pbty is the battery power. The maximum ess discharge
power Pmax is calculated by limiting the output power to one fourth of the open circuit
voltage squared divided by the discharge resistance.
         The SOC block uses an integration of amp-hours from an initial starting point to
determine the SOC. The ess module utilizes look-up tables from MATLAB® script files
for values of SOC-dependent charge internal resistance, discharge internal resistance, and
open circuit voltage. The SOC ranges from 0 to 1.
         ADVISOR simulates the use of a battery pack as numerous batteries in series in
the electrical storage system (ess). These batteries have individual properties of internal
resistance, open-circuit voltage, amp-hour capacity, and minimum and maximum voltage
limits, some of which are temperature dependent. The temperature dependent variables
are the maximum amp-hour capacity, the coulombic efficiency, charge and discharge
internal resistance, and open circuit voltage. They are calculated utilizing linear
interpolation with MATLAB® look-up tables. The temperature range for the data is 0 to
40 degrees C. MATLAB® m-files are the storage structure for the battery information,
allowing for adjustments of the code to be made within these files.
         The standard high-voltage battery pack consists of a series configuration of
twenty-five 12-volt batteries. This pack of twenty-five batteries produces a nominal
voltage of 300 volts with 25 amp-hours of electrical storage capacity. To simulate a 42-
volt system, the battery m-files can be altered to perform as if they are in a combined
series and parallel configuration as shown in Figure 3.




               Figure 3


                                               9
        Since the batteries include a thermal model calculation for internal resistance heat
generation, convective, and conductive heat loss, the simplest way to alter the battery
pack module is by using the standard battery size and thermal properties while
introducing parallel configurations to the battery pack. A parallel battery configuration
allows for identical watt-hours of battery storage as that of the standard high-voltage
battery pack. The Voc of the battery pack, multiplied by the amp-hour Ah capacity is the
watt-hour energy capacity EC of the battery pack, i.e.,

                                          Voc * Ah = EC .                                          (2)

        For purposes of simplification, a set of 24 batteries in series, instead of the
standard 25, can simulate a three-group configuration of sets of batteries in series, with
each of the three sets having eight batteries in parallel configurations. Within the battery
m-files, the Voc would need to be 1/8th the standard battery voltage to reduce the
nominal voltage of the battery packs to about 42 volts:

                                     42V
                                         =
                                           (14 * 3) = 1 .                                          (3)
                                    336V (14 * 24) 8

        The minimum and maximum battery voltage limits also need to be divided by
eight for the 24 batteries in series to simulate the eight parallel groups of three batteries in
series. The amp-hour capacities of the batteries need to be multiplied by eight to keep
the electrical energy capacity of the battery pack the same as the standard high-voltage
pack. The amp-hour capacity of the batteries should be multiplied by eight to simulate
the 8 batteries in parallel producing a total of eight times the amp-hour capacity of a
single battery. For eight batteries in parallel, the internal resistance of the set is governed
by equation 4:

                                           1        1      
                                                = 8         ,                                    (4)
                                          R set    R       
                                                    bty    

where Rset is the internal resistance of the set of batteries, and Rbty is the internal
resistance of a single battery. The resistance of three sets of the 8 batteries (the whole
battery pack) in parallel is shown in equation 5:

                                                            R bty
                                   R tot = 3(R set ) = 3(           ).                             (5)
                                                             8

The 42-volt pack representation using 24 batteries in series requires that the internal
resistance of each battery must be 1/24th of the resistance of the entire pack. Therefore,
the new internal resistance must be 1/64th of the standard battery resistance:

                                         R tot   1   R bty       R bty
                           R bty_new =         =    3            =     .                       (6)
                                         24      24   8
                                                     
                                                                  
                                                                    64


                                                 10
       In order to determine how much power is required from the battery, ADVISOR
uses

                                                   τ
                                     Pbty =               *ω,                                    (7)
                                              eff (ω, τ )

where τ is the torque required from the motor, ω is the angular velocity of the motor
(rad/sec), and eff is the efficiency of the motor which is a function of both τ, and ω.
Since the only input into the motor from the battery is power, and the total power is the
same as that of a 300-volt motor, the changes implemented in ADVISOR are not
necessary.
        The changes made to the motor/controller module were limited to changes of
maximum amperage and minimum motor/controller required voltage. To allow more
current flow through the motor, the maximum amperage limit of the motor/controller
needed to be multiplied by eight. The minimum motor/controller voltage needed to be
divided by eight to allow the low voltage battery pack to power the motor/controller.
        While ADVISOR ensures that the current and voltage used to produce the power
fall within the system capabilities, they are not directly used in the calculations.
Simulations of ADVISOR were completed using a low voltage/high amperage motor and
batteries to verify that the alterations made to the programs were done properly. The
simulations showed that the 42-volt system behaves identically to the standard 300-volt
system if the correct adjustments are made in the ADVISOR code. Simulations were also
completed to show that ADVISOR verifies that the power used is generated from a
voltage and an amperage within the motor/controller limits. In this simulation, the
minimum voltage requirement of the mc was purposefully not met, resulting in erratic
behavior of ADVISOR’s simulation calculations. The GUI output of this simulation can
be seen in Appendix D.
        A 42-volt motor will probably be less efficient in comparison to a 300-volt motor.
Part of the reduced efficiency will be due to the I2R internal resistance power losses of
the motor. The current for a 42-volt motor is eight times greater than that of a 300-volt
motor. Since the maximum power into the motor controller is being held constant, in
order to maintain the same efficiency, the resistance of the wire has to be smaller by a
factor of sixty-four. The only way to achieve this is by using thicker wires which will
have a higher production cost, and may not fit in the size constraints of a starter/alternator
vehicle. As a result, the efficiency of the 42-volt motor will be lower than a 300-volt
motor.

5.      Simulation Procedure
In order to determine what motor and engine sizes would best optimize the performance
of the HEV, a number of simulations were run. The simulations were run for both urban
and highway drive cycles. This data determined how different configurations affect
emissions and fuel efficiency. The motor sizes ranged from 5 kW to 200 kW. The
engine sizes ranged from 50 kW to 200 kW.




                                                11
6.      Results and Discussion
The focus of this project was modeling a parallel 42-volt starter/alternator configuration
SUV. The main objective was to find the optimal engine and motor size in order to
maximize fuel efficiency and reduce emissions.
        Initially, simulations were run varying both the engine size and the motor size.
For a given engine size, the motor size was varied from 5 to 100 kW. Fuel efficiency
decreased as motor size increased. The simulations were run for both urban (UDDS) and
highway (HWY) drive cycles. The best fuel efficiency occurred when using motor sizes
of 5 and 25 kW as shown in Figure 5. The difference of the fuel efficiency within that
range was small enough (0.5 mpg) that for the rest of the simulations, an intermediate
motor size of 15 kW was used. The raw data for these simulations can be found in
Appendix E.

                                              Fuel Efficiency Vs. Motor Size (HEV,HWY)

                                  14.4

                                  14.2

                                   14
          Fuel Efficiency (mpg)




                                  13.8

                                  13.6                                                   175 kW engine
                                  13.4                                                   200 kW engine

                                  13.2

                                   13

                                  12.8

                                  12.6
                                         0   20     40      60          80   100   120
                                                      Motor Size (kW)


        Figure 4

        Once the motor size was determined, more simulations were run to determine the
best engine size. The engine size was varied, for the starter/alternator and conventional
vehicles, from 40 to 200 kW for the UDDS and HWY drive cycles. For very small
engine sizes, the HEV was unable to achieve the drive cycle requirements. In the
simulations, engine sizes of 70 to 200 kW were used for the UDDS drive cycle.
Similarly, the HEV data only ranges from 140 to 200 kW for the HWY drive cycle. For
the conventional vehicle, the data ranges from 50 to 200 kW for the UDDS drive cycle,
and from 110 to 200 kW for the HWY drive cycle. For the UDDS drive cycle, fuel
efficiency for the HEV and conventional vehicles decreased as the engine size increased
as shown in Figures 5 and 6. A similar trend was found for the HWY drive cycle shown
in Figures E.1 and E.2 in Appendix E.




                                                                  12
                                              Fuel Efficiency Vs. Engine Size (HEV, UDDS)

                                    25

         Fuel Efficiency (MPG)
                                    20

                                    15

                                    10

                                     5

                                     0
                                         50        70       90    110        130     150   170   190
                                                                 Engine Size (kW)

       Figure 5


                                                        Fuel Efficieny Vs. Engine Size
                                                           (Conventional, UDDS)

                                    25
            Fuel Efficiency (mpg)




                                    20


                                    15


                                    10


                                    5


                                    0
                                         50       70       90     110        130     150   170   190

                                                                  Engine Size (kW)

       Figure 6

ADVISOR has empirical data tables for emissions specific to each engine. The program
also models all the emissions from the engine to the tailpipe. For each simulation,
ADVISOR outputs values in parts per million (PPM) for emissions of HC, CO, and
NOx. In general, for the UDDS drive cycle, the emissions increased as the engine size
increased for both the HEV and conventional vehicles as shown in Figures 7 and 8. A
similar trend was seen for the HWY drive cycle as shown in Figures E.3 and E.4 in
Appendix E.



                                                                        13
                                            Emissions Vs. Engine Size (HEV, UDDS)

                              100

           Emissions (PPM)

                               10
                                                                                           HC
                                                                                           CO
                                                                                           NOx
                                1
                                        0        50     100          150    200    250


                              0.1
                                                       Engine Size (kW)

       Figure 7




                                                 Emissions Vs. Engine Size
                                                   (Conventional,UDDS)
                              100
            Emissions (PPM)




                              10
                                                                                            HC
                                                                                            CO
                                                                                            NOx

                               1
                                    0            50      100          150    200     250



                              0.1
                                                         Engine Size (kW)


       Figure 8

        An overall performance rating was calculated for each simulation run. The
performance rating takes into account the vehicle fuel efficiency, emissions, acceleration,
weight, and grade achievable (55 mph). In order to calculate the performance rating, the
fuel efficiency, emissions, acceleration, weight, and grade achievable had to be made
dimensionless. These values were made dimensionless by dividing by the corresponding


                                                                14
values for the conventional vehicle of identical engine size. A weighting factor was
assigned to each these ratios according to their importance. Next, each of the ratios were
multiplied by their weighting factors and summed. Subtracting 6 (the conventional
vehicle performance rating) from these numbers give the performance rating of the HEV
relative to a conventional vehicle. A copy of the spreadsheet including the calculations
for the performance rating is included in Appendix E. For the UDDS drive cycle, the
performance rating decreased as the engine size increased as shown in Figure 9. An
improvement of the HEV over the conventional vehicle is only seen for motors size less
than 150 kW.


                           Performance Rating Vs. Engine Size (UDDS)


                    0.6
                    0.5
                    0.4
                    0.3
           Rating




                    0.2
                    0.1
                      0
                    -0.1 60     80    100   120        140   160   180   200
                    -0.2
                                            Engine Size (kW)


       Figure 9

There was almost no relation between engine size and performance rating when
simulating the HEV under highway conditions as shown in Figure 10. Under higher
torque loads, experienced during the HWY drive cycle, the engines operate at
approximately the same efficiency.




                                                  15
                          Performance Rating Vs. Engine Size (HWY)

                   0.4

                   0.3

                   0.2
          Rating




                   0.1

                      0
                       130    140   150   160    170   180   190   200    210
                   -0.1

                   -0.2
                                          Engine Size (kW)

       Figure 10

         The main objective of maximizing fuel efficiency and reducing emissions is
accomplished at smaller engine sizes. The higher performance rating at smaller engine
sizes is due to the manner in which the performance rating was calculated since increased
fuel efficiency and decreased emission levels were given the most consideration. At
larger engine sizes, the increased weight of the vehicle decreases the fuel efficiency.
Additionally, the larger engine causes an increase in the emissions.

7.      Conclusions
The simulation program used for modeling HEVs was ADVISOR. It allowed for the
largest range of vehicles and drive cycles to be simulated. It also had the most
comprehensive set of outputs. It is the most up to date simulator available to the public
and allows the user to modify the components. For these reasons, it is the simulator of
choice.
        The simulation of a 42-volt starter/alternator HEV in ADVISOR in conjunction
with the performance rating above showed smaller engines and motors will maximize
fuel efficiency and lower emissions in the UDDS drive cycle. However, the smaller
combinations of engines and motors are unable to perform at an acceptable level when
using the HWY drive cycle. Therefore, in order to accommodate both drive cycles, a 140
kW engine, coupled with a 15 kW motor is the preferred combination.
        The modification of ADVISOR to accommodate a 42-volt configuration was done
by changing the MATLAB® files associated with the energy storage system and the
motor used. The important variables used in ADVISOR’s simulations are the power
generated by the batteries and power required by the motor. Because the manner in
which the files were changed kept the power constant, the changes in ADVISOR’s code
were not necessary.




                                                16
8.       Limitations of this Study
This paper explains the manner in which ADVISOR simulates a 42-volt hybrid electric
vehicle using a starter alternator model under a parallel configuration. Changes were
successfully implemented in the energy storage system. However changes were not
made to the motor efficiency map used in ADVISOR. The efficiency map used by
ADVISOR gives the efficiency of the motor at a range of torques and speeds. The
efficiency map used in these simulations is based on empirical data from a motor
designed to operate at a nominal 300 volts. Replacing the current mc efficiency map with
one designed to model a 42-volt motor will yield more accurate results.
         The current version of ADVISOR does not take into account regenerative braking
in starter/alternator model. Regenerative braking will increase fuel efficiency and
possibly reduce emissions. Future versions of ADVISOR will model regenerative
braking. The use of a newer version will provide a more realistic model of current
technology.
         When running simulations using ADVISOR, the first simulation results in
erroneous data. In order to overcome this, the first simulation after either the drive train
configuration or drive cycle is changed should be disregarded




                                            17
REFERENCES

[1] J. Motavalli, Forward Drive, San Francisco: Sierra Club Books, 2000.
[2] http://www.ott.doe.gov/hev/
[3] http://www.ai-online.com/articles/mar00/0300f4.htm
[4] http://www.polk.com/news/releases/2001_0104d.asp
[5] Consumer Reports – Cars 2001 Annual Auto Issue, April 2001 pg 23.
[6] Cole, G.H., “SIMPLEV: A Simple Electric Vehicle Simulation Program, Version
2.0.,” EG&G Idaho, Inc. April1993.
[7] E-mail correspondence with Giorgio Rizzoni – rizzoni.1@osu.edu
[8] K. B. Wipke, M. R. Cuddy, and S. D. Burch, “ADVISOR 2.1: A User-Friendly
Advanced Powertrain Simulation Using a Combined Backward/Forward Approach,”
NREL/JA-540-26839, September 1999.
[9] ADVISOR documentation
[10] http://www.ctts.nrel.gov/analysis/reading_room.html




                                        18
Appendix A. Sample MATLAB® Code (mc file)




           Appendix A. Sample MATLAB® Code




                                   19
Example of MATLAB® motor controller script file.

% ADVISOR Data file: MC_AC75.m
%
% Data source:
% Lester, L.E., et al., "An Induction Motor Power Train for EVs--The
Right
% Power at the Right Price," reprinted in Proceedings: Advanced
Components for
% Electric and Hybrid Electric Vehicles, 10/27-28/93, Gaithersburg, MD.
% Mr. Lester was employed with Westinghouse in Maryland at that time,
and may
% be still.
%
% Data confidence level: Good: data from a published paper
%
% Notes: This is a Westinghouse, 75 kW, AC Induction motor
%         Efficiency/loss data appropriate for a 320 V system.
%
% Created on: 6/15/98
% By: MRC & KW
%
% Revision history at end of file.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% FILE ID INFO
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
mc_description='Westinghouse 75-kW (continuous) AC induction
motor/inverter';
mc_version=3.0; % version of ADVISOR for which the file was generated
mc_proprietary=0; % 0=> non-proprietary, 1=> proprietary, do not
distribute
mc_validation=0; % 0=> no validation, 1=> data agrees with source data,
% 2=> data matches source data and data collection methods have been
verified
disp(['Data loaded: MC_AC75 - ',mc_description]);


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% SPEED & TORQUE RANGES over which data is defined
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% (rad/s), speed range of the motor
mc_map_spd=[0 1000 2000 3000 4000 5000 6000 7000 8000 9000
10000]*(2*pi/60);
% Note: the above conversion from RPM to rad/s was fixed 6/16/98

% (N*m), torque range of the motor
mc_map_trq=[-200 -180 -160 -140 -120 -100 -80 -60 -40 -20 ...
   0 20 40 60 80 100 120 140 160 180 200]*4.448/3.281;


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% EFFICIENCY AND INPUT POWER MAPS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% (--), efficiency map indexed vertically by mc_map_spd and
% horizontally by mc_map_trq



                                        20
mc_eff_map=[...
0.7   0.7   0.7    0.7    0.7    0.7    0.7    0.7    0.7    0.7    0.7   0.7    0.7    0.7
0.7   0.7   0.7    0.7    0.7    0.7    0.7
0.78 0.78 0.79     0.8    0.81   0.82   0.82 0.82     0.81   0.77   0.7   0.77   0.81   0.82
0.82 0.82 0.81     0.8    0.79   0.78   0.78
0.85 0.86 0.86     0.86   0.87   0.88   0.87 0.86     0.85   0.82   0.7   0.82   0.85   0.86
0.87 0.88 0.87     0.86   0.86   0.86   0.85
0.86 0.87 0.88     0.89   0.9    0.9    0.9    0.9    0.89   0.87   0.7   0.87   0.89   0.9
0.9   0.9   0.9    0.89   0.88   0.87   0.86
0.81 0.82 0.85     0.87   0.88   0.9    0.91 0.91     0.91   0.88   0.7   0.88   0.91   0.91
0.91 0.9    0.88   0.87   0.85   0.82   0.81
0.82 0.82 0.82     0.82   0.85   0.87   0.9    0.91   0.91   0.89   0.7   0.89   0.91   0.91
0.9   0.87 0.85    0.82   0.82   0.82   0.82
0.79 0.79 0.79     0.78   0.79   0.82   0.86 0.9      0.91   0.9    0.7   0.9    0.91   0.9
0.86 0.82 0.79     0.78   0.79   0.79   0.79
0.78 0.78 0.78     0.78   0.78   0.78   0.8    0.88   0.91   0.91   0.7   0.91   0.91   0.88
0.8   0.78 0.78    0.78   0.78   0.78   0.78
0.78 0.78 0.78     0.78   0.78   0.78   0.78 0.8      0.9    0.92   0.7   0.92   0.9    0.8
0.78 0.78 0.78     0.78   0.78   0.78   0.78
0.78 0.78 0.78     0.78   0.78   0.78   0.78 0.78     0.88   0.92   0.7   0.92   0.88   0.78
0.78 0.78 0.78     0.78   0.78   0.78   0.78
0.78 0.78 0.78     0.78   0.78   0.78   0.78 0.78     0.8    0.92   0.7   0.92   0.8    0.78
0.78 0.78 0.78     0.78   0.78   0.78   0.78];

%if ~exist('mc_inpwr_map')
 % disp('Converting: MC_AC75 motor map efficiency data --> power loss
data')
   %% find indices of well-defined efficiencies (where speed and torque
> 0)
   pos_trqs=find(mc_map_trq>0);
   pos_spds=find(mc_map_spd>0);

   %% compute losses in well-defined efficiency area
   [T1,w1]=meshgrid(mc_map_trq(pos_trqs),mc_map_spd(pos_spds));
   mc_outpwr1_map=T1.*w1;
   mc_losspwr_map=(1./mc_eff_map(pos_spds,pos_trqs)-1).*mc_outpwr1_map;

   %% to compute losses in entire operating range
   %% ASSUME that losses are symmetric about zero-torque axis, and
     %% ASSUME that losses at zero torque are the same as those at the
lowest
     %% positive torque, and
     %% ASSUME that losses at zero speed are the same as those at the
lowest
     %% positive speed
   mc_losspwr_map=[fliplr(mc_losspwr_map) mc_losspwr_map(:,1)
mc_losspwr_map];
   mc_losspwr_map=[mc_losspwr_map(1,:);mc_losspwr_map];

   %% compute input power (power req'd at electrical side of
motor/inverter set)
   [T,w]=meshgrid(mc_map_trq,mc_map_spd);
   mc_outpwr_map=T.*w;
   mc_inpwr_map=mc_outpwr_map+mc_losspwr_map;
%end




                                        21
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% LIMITS
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% max torque curve of the motor indexed by mc_map_spd
mc_max_trq=[200 200 200 175.2 131.4 105.1 87.6 75.1 65.7 58.4 52.5]*...
   4.448/3.281; % (N*m)

% maximum overtorque capability (not continuous, because the motor
would overheat)
mc_overtrq_factor=1.8; % (--), estimated

mc_max_crrnt=480; % (A), maximum current allowed by the controller and
motor
mc_min_volts=120; % (V), minimum voltage allowed by the controller and
motor


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% DEFAULT SCALING
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% (--), used to scale mc_map_spd to simulate a faster or slower running
motor
mc_spd_scale=1.0;

% (--), used to scale mc_map_trq to simulate a higher or lower torque
motor
mc_trq_scale=1.0;


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% OTHER DATA
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
mc_inertia=0; % (kg*m^2), rotor inertia; unknown
mc_mass=91; % (kg), mass of motor and controller

% motor/controller thermal model
mc_th_calc=1;                              % --     0=no mc thermal
calculations, 1=do calc's
mc_cp=430;                                 % J/kgK ave heat capacity of
motor/controller (estimate: ave of SS & Cu)
mc_tstat=45;                               % C      thermostat temp of
motor/controler when cooling pump comes on
mc_area_scale=(mc_mass/91)^0.7;            % --     if motor dimensions
are unknown, assume rectang shape and scale vs AC75
mc_sarea=0.4*mc_area_scale;                % m^2    total module surface
area exposed to cooling fluid (typ rectang module)

%the following variable is not used directly in modelling and should
always be equal to one
%it's used for initialization purposes
mc_eff_scale=1;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% CLEAN UP
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
clear T w mc_outpwr1_map mc_losspwr_map T1 w1 pos_spds pos_trqs



                                   22
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% REVISION HISTORY
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% 6/12/98 (KW): converted data from A1.2.1 into A2 (as
MC_WESTINGHOUSE), have not yet verified
% 6/15/98 (KW): combined with MRC's MC_AC75.m and replaced both with
new one
% 6/16/98 (KW): speed vector multiplier from RPM to rad/s was correctly
inverted
% 6/23/98 (MC): disabled existence check preceding computation of input
power map
% 6/30/98 (MC): cosmetic changes
% 2/3/99 (SB): added thermal model variables
% 3/15/99:ss updated *_version to 2.1 from 2.0




% 11/03/99:ss updated version from 2.2 to 2.21




                                   23
Appendix B. Important ADVISOR Modules




       Appendix B. Important ADVISOR Modules




                                  24
Electric Assist Control Strategy – see Figure B.1

The first Simulink® module necessary to understand is the electric assist control strategy
labeled <sc> in Figure 1. This module uses as its input the total torque and speed
required (into the clutch) to accelerate the vehicle. Its output is the torque and speed
required from the engine. When this module is opened, the mathematical calculations
inside became apparent. Figure B.1, showing the opened electric assist control module,
provides a clear example of the Simulink® programming environment.




       Figure B.1

       This block uses the torque and speed of the clutch to calculate the torque
requirement from the engine for motion. This calculation is performed in the block
labled minimum trq where the torque and speed requirement from the clutch are
converted to the tractive torque requirement τT from the engine using linear interpolation
of empirical values specific to the engine used.
        Another set of calculations performed within this block concern the recharging of
the batteries. Based on the batteries’ state of charge, the torque required for charging the
batteries τC is calculated. These calculations are performed in the block labeled chg trq
req’d. The actual state of charge of the battery is compared to the state of charge goal,
60%. If the batteries need to be recharged, τC is positive; if the batteries do not need to
be recharged, τC is negative. This number τC is added to τT giving a combined torque
requirement from the engine τSUM which is then compared to τT. This comparison is the
MinMax block. If the batteries need to be recharged and the engine is on, the entire
torque τSUM is passed as a requirement to the engine. If the batteries do not need to be
recharged, and the engine is on, only the original torque for motion τT is passed on.



                                             25
Motor/Controller – see Figure B.2

Another Simulink® module necessary to understand is the motor/controller <mc>
module. The backward calculation inputs to the motor controller are the torque and
speed required at the motor input to the torque coupler. The open <mc> module is shown
in Figure B.2. This Figure shows both forward and backward-facing calculations, the
backward calculations are performed in the “required” branch, and the forward
calculations are performed in the “available“ branch. The connection between the two
demonstrates ADVISOR’s assumption that the motor will be as efficient in the forward
calculations as it was calculated to be in the backward calculations.
       The Saturation block places bounds on the speed. The lower bound is zero, and
the upper bound is the maximum speed of the motor being used. The next block is the
motor speed estimator block. The input into this block is the motor’s speed. If the
calculated vehicle speed falls short of the desired vehicle speed by more than one mile
per hour during the current time step, the motor’s speed from the previous time step is
used. The effect of inertia block uses the motor’s speed as its input. This block
calculates the torque τINT needed to overcome the effects of inertia in order to accelerate
the motor. It also assures that this torque is not greater than the product of the maximum
motor torque and the fractional contribution of the motor’s inertia to the total vehicle
inertia. The motor controller module then sums the torque required at the motor input
and τINT and passes it to the enforce torque limit block. This block again enforces
the maximum torque production of the motor used. The next block is the 2-D lookup
table block. It uses the motor’s speed and torque along with the motors specifications to
output the power the motor requires from the power bus. The final block in the motor
controller module simply passes the speed at which the motor is required to turn along
with the power the motor requires to the user’s workspace. Finally, this module sends the
power Pmotor it calculated to the power bus as a requirement of the motor.




Figure B.2



                                            26
Power bus – see Figure B.3
Since there is no generator in the starter alternator model, the power bus module simply
dictates how much power is required from the batteries. These calculations are very
simple. The backward calculations, the “required” branch in Figure B.3, will be
discussed first. It should be noted that both the “power available from generator” and the
“power req’d from generator” path lead nowhere when using the starter alternator model.




Figure B.3

        In the backward calculation path, Pmotor is added to the power required by the
accessories after it has been adjusted for efficiency specified by the vehicle choice. This
sum is then passed to the battery block as the power Pbty required from the batteries.
There are switches throughout this block that ensure the vehicle being simulated is
equipped with a battery storage system.
        In the forward calculations, if the motor requires power and the battery can supply
power, the power required from the accessories is subtracted from the power available
from the batteries and passed as the power available from the power bus. If the motor
does not require power or the battery cannot supply power, the power available from the
power bus is zero. This demonstrates the way in which ADVISOR incorporates
backward and forward calculations to ensure valid results.




                                            27
Energy Storage System – see Figure B.4

The ess module has only one input, Pbty the power required from the power bus module.
Before it begins calculations with Pbty , the battery state of charge (SOC) from the
previous time step along with the battery’s temperature are used to calculate a single
battery’s open circuit voltage Vocbatt along with its resistance to charging and
discharging. These three values are calculated using two dimensional lookup tables
specified in the ess m-file dictated by the user’s choice of battery. The entire pack open-
circuit voltage Voc is calculated by multiplying the number of batteries by Vocbatt.
Depending upon whether Pbty is positive or negative during the current time step, the
resistance Rintpack of the pack is calculated by multiplying the charging or discharging
resistance of a single battery by the number of batteries. These calculations are all done
in the block labeled pack Voc Rint in Figure B.4. In the block labeled limit power,
the minimum voltage at which the motor will operate along with the maximum and
minimum battery voltage are used to limit the discharge power of the battery during the
time step.




Figure B.4

        In the compute current block, the limited discharge power, Voc, and Rintpack
are used to calculate the current I from the battery pack. The fact that Rintpack and Voc
determine the battery power according to equation B-1 allows for the calculation of the
current by solving the quadratic equation for the variable I:
                              Rint pack I 2 − VocI + Pbty = 0 .                           (B-1)
This block also assures the current computed does not exceed the current limit based on
the batteries’ maximum voltage. Additionally, this block calculates the voltage and
power available to the bus used in the power bus’ forward calculations:


                                            28
                                Vbus_a = Voc - (I * Rint pack )                              (B-2)

                                     Pbus_a = Vbus_a * I .                                   (B-3)
The SOC algorithm block calculates the state of charge (SOC) for the current time step
using Ipack from the “compute current” block. The state of charge is a number between 0
and 1 representing the amount of power in the battery pack during the current time step.
The SOC is given by:
                                 Ah cap − Ah used
                                                  = SOC .                                (B-4)
                                      Ah cap

The Amp hours used Ahused are subtracted from the maximum Amp hour capacity Ahcap.
This difference is then divided by Ahcap. Ahused is calculated by integrating the current
from the battery pack over the time that has passed, using the Amp hours depleted at the
outset as the initial condition. The block labeled “max pack pwr” simply limits the output
power to one fourth of the open circuit voltage squared divided by the discharge
resistance.




                                             29
Appendix C. Forward and Backward-Facing Simulation Diagrams




Appendix C. Forward and Backward-Facing Simulation
                     Diagrams




                                    30
                                                                                                     Electric
                                                                                 Clutch               Assist                         Fuel
                                                                                  <cl>               Control                       Converter
                                                     <vc> par                                        Strategy             8          <fc>
              <sdo> par
                                                                                                      <cs>




                                                                            5                                        7
                                                                                           6



  Drive          Vehicle                                                                                                                           Power
                                       Wheel              Final                                  Torque                        Motor/
  Cycle          <veh>                                                    Gearbox                                                                   Bus
                                        and               Drive                                  Coupler                      controller
  <cyc>   1                      2               3                  4      <gb>                                  9                          10     <pb>
                                        axle              <fd>                                    <tc>                          <mc>                               11
                                       <wh>



                                                                                                                                                           Energy
                                                                                                                                                           Storage
                                                                                                                                                            <ess>




              Figure C.1 Backward-Facing ADVISOR diagram




                                                                                                  Electric
                                                                            Clutch                 Assist                         Fuel
                                                                             <cl>                 Control                       Converter
                                                <vc> par                                          Strategy                        <fc>
          <sdo> par
                                                                                                   <cs>




                                                                                                                         104
                                                                           106            105




Drive         Vehicle                                                                                                                            Power
                                     Wheel             Final                                   Torque                     Motor/
Cycle         <veh>                                                     Gearbox                                                                   Bus
                           109        and              Drive                                   Coupler                   controller
<cyc>                                          108                107    <gb>                              103                                   <pb>         101
                                      axle             <fd>                                     <tc>                       <mc>     102
                                     <wh>



                                                                                                                                                         Energy
                                                                                                                                                         Storage
                                                                                                                                                          <ess>




              Figure C.2 Forward-Facing ADVISOR diagram




                                                                                31
Appendix D. ADVISOR Output – Incorrectly Modified Motor File




 Appendix D. ADVISOR Output – Incorrectly Modified
                   Motor File




                                     32
       Figure D.1 ADVISOR Output

Advisor was run using a 42-volt battery pack and a standard 300-volt motor. Since the
motor’s minimum voltage limit was not met by the battery pack, a malfunction occurred.
The red trace in Figure D.1 shows that Advisor’s calculations of the vehicle speed missed
the speed trace that a completely unmodified or correctly modified vehicle would make.




                                           33
Appendix E. Raw Data and Calculations




           Appendix E. Raw Data and Calculations




                                        34
The urban drive cycle, 24 batteries, based on 41 kW engine efficiencies and emissions,starter/alternator.
  TEST:       UDDS             HEV
Motor kW Engine kW Fuel Efficiency HC               CO    Nox 0-60MPH Max accel(ft/s2)
               <75       Missed Trace
    25          75             22.9         1.613 21.101 0.72       16.1           8.5
    50          75             22.3          1.43 17.032 0.67       16.3           8.4
    75          75
   100          75
     5         100             19.8         2.046 29.906 0.77       12.1          11.1
    25         100             19.6          2.05 29.83 0.78        12.1           11
    50         100             19.2         1.776 23.181 0.7        12.3          10.8
    75         100             18.8         2.063 29.603 0.81       12.5          10.7
   100         100             18.4         2.071 29.454 0.83       12.6          10.5
    25         150             14.5         2.506 34.433 0.8         ??           14.2
    50         150             14.3         3.347 54.47 1.08          9           14.2

The urban drive cycle, 15 batteries, based on 41 kW engine efficiencies and emissions,starter/alternator.
    50         150             14.2         3.359 54.058 1.09        8.7          14.2

The urban drive cycle, 15 batteries, based on 103 kW engine efficiencies and emissions,starter/alternator.
    25         150             15.3         2.999 17.738 2.1        9.4           14.2

The highway drive cycle, 24 batteries, based on 41 kW engine efficiencies and emissions,starter/alternator.
  TEST:        HWY              HEV
Motor kW Engine kW Fuel Efficiency HC               CO     Nox 0-60MPH Max accel(ft/s2)
 5 to 200    0 to 125      Missed Trace
     5          150          MT/15.6         3.77 60.365 1.85        8.9          14.2
    25          150             15.6        3.765 56.044 1.82        8.9          14.2
    50          150             15.4        3.769 56.945 1.84         9           14.2
    75          150             15.3        3.785 58.166 1.87         9           14.2
    100         150             15.1        3.765 59.081 1.88        9.1          14.2
     5          175             14.2         4.23 51.311 1.98        8.3          14.2
    25          175             14.3        4.506 58.786    2        8.2          14.2
    50          175             14.1         4.52 59.905 2.02        8.2          14.2
    75          175              14          4.51 61.286 2.03        8.3          14.2
    100         175             13.8        4.511 62.33 2.07         8.4          14.2
     5          200              13         4.908 63.051 2.07        7.8          14.2
    25          200              13         5.178 61.378 2.12        7.7          14.2
    50          200             12.9        5.201 61.467 2.15        7.8          14.2
    75          200             12.8        5.225 61.774 2.19        7.8          14.2
    100         200             12.7         5.24 62.704 2.22        7.8          14.2

The highway drive cycle, 15 batteries, based on 41 kW engine efficiencies and emissions, starter/alternator.
    5           150             15.4        4.214 59.917 2.13        8.7          14.2
    25          150             15.3        3.796 59.03 1.85         8.6          14.2
    50          150             15.2        3.797 60.437 1.86        8.7          14.2

The highway drive cycle, 24 batteries, based on 41 kW engine efficiencies and emissions, parallel config.

    25          150             15.7        2.807 34.716 1.37        7.6            14.2
    50          150             15.6        3.811 49.012 1.88        7.7            14.2
    75          150             15.4        3.836 50.747 1.9         7.7            14.2


                                                       35
The urban drive cycle, based on 41 kW engine efficiencies and emissions,conventional.
     TEST:             UDDS            Conventional
    Engine        Fuel Efficiency           HC                   CO           Nox       0-60MPH Max accel(ft/s2)

      100              18.1                 1.868                13.83        0.688       11.9        11.6
      125              15.7                 2.646                 20          0.855        9.8        13.9
      150              13.9                  3.28               24.814        0.995       8.6         14.1
      175              12.5                 3.957               29.878        1.148         8         14.2
      200              11.4                 4.636               35.713        1.279        7.5        14.2

The highway drive cycle, based on 41 kW engine efficiencies and emissions,conventional.
     TEST:              HWY            Conventional
    Engine        Fuel Efficiency           HC                     CO          Nox      0-60MPH Max accel(ft/s2)
      100          Missed Trace
      125               16.6               2.506                 53.462       1.275        9.8       13.9
      150               15.1                3.64                 66.505       1.656        8.6       14.1
      175               13.8               4.355                  54.38       2.008         8        14.2
      200               12.6               4.985                 54.769       2.197        7.5       14.2




                                                       36
The urban drive cycle, 24 batteries, based on 41 kW engine efficiencies and emissions,starter/alternator.
     TEST:              UDDS                 HEV
Weight Factors:                                5         -0.333333 -0.333333 -0.333333             -1             1            1        1
   Motor kW          Engine kW          Fuel Efficiency      HC          CO         NOx       0-60MPH       Max accel(ft/s2)   wt     grade
       15                 40
       15                 50
       15                 60                mt/25.1                                                                            1942
       15                 70                 23.7           1.436       17.942     0.669           17             8            1976   11.8
       15                 80                 22.4           1.657       22.377     0.706           15            9.1           2011   13.7
       15                 90                 20.9           1.877       26.676     0.747          13.2           10.1          2045   15.7
       15                100                 19.7           2.11        31.229     0.791          12.1           11.1          2080   17.5
       15                110                 18.4           2.367       35.751     0.851          11.1            12           2115   19.4
       15                120                 17.3           2.618       40.304     0.905          10.3           12.9          2149   21.2
       15                130                 16.3           2.884       45.603     0.964           9.6           13.8          2184   22.9
       15                140                 15.4           3.152       51.054     1.019           9.2           14.2          2218   24.7
       15                150                 14.6           3.444       56.886     1.082           8.9           14.2          2253   26.3
       15                160                 13.9           3.764       62.855     1.165           8.6           14.2          2288    28
       15                170                 13.2           4.084       68.978     1.242           8.3           14.2          2322   29.6
       15                180                 12.7           4.396       75.332     1.311            8            14.2          2357   31.2
       15                190                 12.2           4.72        81.855     1.384           7.8           14.2          2391   32.7
       15                200                 11.7           4.77        83.408     1.379           7.7           14.2          2426   33.8

The highway cycle, 24 batteries, based on 41 kW engine efficiencies and emissions,starter/alternator.
     TEST:              HWY                  HEV
   Motor kW          Engine kW         Fuel Efficiency        HC         CO         Nox        0-60MPH      Max accel(ft/s2)    wt    grade
       15                100                                                                     12.1            11.1          2080    17.5
       15                110                                                                     11.1             12           2115    19.4
       15                120                                                                     10.3            12.9          2149    21.2
       15                130               mt/16.8           3.274     67.508      1.614          9.6            13.8          2184    22.9
       15                140                 16.2            3.616     59.119      1.815          9.2            14.2          2218    24.7
       15                150                 15.6            3.685     54.197      1.787          8.9            14.2          2253    26.3
       15                160                 15.1            4.116     58.839      1.945          8.6            14.2          2288     28
       15                170                 14.5            4.442     60.011       1.99          8.3            14.2          2322    29.6
       15                180                  14             4.736      58.87      2.086           8             14.2          2357    31.2
       15                190                 13.5            5.004     59.289      2.128          7.8            14.2          2391    32.7
       15                200                  13             5.082     60.101      2.065          7.7            14.2          2426    33.8




                                                                       37
The urban drive cycle, based on 41 kW engine efficiencies and emissions,conventional.
     TEST:              UDDS          Conventional Vehicle
Weight Factors:            5              -0.333333333          -0.333333 -0.333333        -1           1              1      1
     Engine        Fuel Efficiency              HC                  CO        Nox       0-60MPH   Max accel(ft/s2)    wt    grade
       40                 mt                                                                                         1590
       50                24.5                  1.11               11.813     0.619       24.8            6           1625    7.7
       60                23.3                  1.31               11.317     0.649        20            7.2          1660    9.9
       70                21.9                 1.525               12.065     0.689       16.9           8.4          1694    12
       80                20.5                  1.75               13.545     0.729       14.7           9.5          1729    14
       90                19.2                  2.02               15.339     0.801       13.1          10.5          1763    16
      100                18.1                 2.277               17.273     0.86        11.9          11.6          1798   17.8
      110                 17                  2.493               19.474     0.887       10.9          12.6          1833   19.6
      120                16.1                 2.752               21.254     0.931       10.1          13.5          1867   21.4
      130                15.3                 2.983               23.082     0.977       9.5           14.1          1902    23
      140                14.5                 3.274               25.049     1.057         9           14.1          1936   24.7
      150                13.9                 3.555               26.834     1.123       8.6           14.1          1971   26.3
      160                13.3                 3.841               28.644     1.189       8.3           14.2          2006   27.8
      170                12.8                 4.116               30.828     1.243         8           14.2          2040   29.3
      180                12.3                 4.387               33.368     1.289       7.9           14.2          2075   30.7
      190                11.8                 4.682               35.955     1.358       7.7           14.2          2109   32.1
      200                11.4                 4.883                37.74     1.383        7.5          14.2          2144   33.4


The highway cycle, based on 41 kW engine efficiencies and emissions,conventional.
     TEST:              HWY         Conventional Vehicle
     Engine        Fuel Efficiency              HC                CO         Nox        0-60MPH   Max accel(ft/s2)   wt     grade
       100               mt
       110              17.5                  2.548              67.635     1.351        10.9          12.6          1833   19.6
       120               17                   2.894              64.648     1.475        10.1          13.5          1867   21.4
       130              16.3                  3.175              58.519     1.593        9.5           14.1          1902    23
       140              15.7                  3.484              67.478     1.632         9            14.1          1936   24.7
       150              15.1                  3.763              67.808     1.719        8.6           14.1          1971   26.3
       160              14.6                  4.065              59.588     1.933        8.3           14.2          2006   27.8
       170              14.1                  4.366              57.866      2.03         8            14.2          2040   29.3
       180              13.5                  4.615              65.377     2.043        7.9           14.2          2075   30.7
       190              13.1                  4.879              60.632     2.151        7.7           14.2          2109   32.1
       200              12.6                  5.151              56.647     2.267        7.5           14.2          2144   33.4




                                                                     38
                                      Fuel Efficiency Vs. Engine Size
                                                 (HWY, HEV)

                            25


                            20
   Fuel Efficiency (m pg)




                            15


                            10


                            5


                            0
                                 50            100              150     200
                                                 Engine Size (kW)


Figure E.1



                                      Fuel Efficiency Vs. Engine Size
                                           (HWY, Conventional)

                            25


                            20
   Fuel Efficiency (m pg)




                            15


                            10


                            5


                            0
                                 50           100               150     200
                                                 Engine Size (kW)



Figure E.2




                                                           39
                  Em issions Vs. Engine Size
                          (HWY,HEV)


       1 00




                                                                   HC
        10                                                         CO
                                                                   Nox




         1
              0      50        1 00        1 50        200   250

                          E n g i n e S i z e ( k W)



Figure E.3




                  Em issions Vs. Engine Size
                      (HWY,Conventional)


       1 00




                                                                   HC
        10                                                         CO
                                                                   Nox




         1
              0      50        1 00        1 50        200   250

                          E n g i n e S i z e ( k W)



Figure E.4



                                                  40
Performance Rating
Calculations
UDDS Calculations
Relative weight factors               5          -0.3333 -0.33333 -0.333    -1       1              1      1
   Motor kW        Engine kW   Fuel Efficiency     HC       CO     NOx 0-60MPH Max accel(ft/s2)    wt    grade       Rating
       15              40        #VALUE!         #DIV/0! #DIV/0! #DIV/0! #DIV/0!  #DIV/0!           0   #DIV/0!     #VALUE!
       15              50             0             0        0       0      0        0              0      0           -6
       15              60        #VALUE!            0        0       0      0        0            1.170    0        #VALUE!
       15              70           1.082         0.942    1.487 0.971    1.006    0.952          1.166 0.983        0.374
       15              80           1.093         0.947    1.652 0.968    1.020    0.958          1.163 0.979        0.353
       15              90           1.089         0.929    1.739 0.933    1.008    0.962          1.160 0.981        0.338
       15             100           1.088         0.927    1.808 0.920    1.017    0.957          1.157 0.983        0.304
       15             110           1.082         0.949    1.836 0.959    1.018    0.952          1.154 0.990        0.241
       15             120           1.075         0.951    1.896 0.972    1.020    0.956          1.151 0.991        0.177
       15             130           1.065         0.967    1.976 0.987    1.011    0.979          1.148 0.996        0.129
       15             140           1.062         0.963    2.038 0.964    1.022    1.007          1.146 1.000        0.119
       15             150           1.050         0.969    2.120 0.963    1.035    1.007          1.143 1.000        0.016
       15             160           1.045         0.980    2.194 0.980    1.036    1.000          1.141 1.007        -0.048
       15             170           1.031         0.992    2.238 0.999    1.038    1.000          1.138 1.010        -0.142
       15             180           1.033         1.002    2.258 1.017    1.013    1.000          1.136 1.016        -0.123
       15             190           1.034         1.008    2.277 1.019    1.013    1.000          1.134 1.019        -0.126
       15             200           1.026         0.977    2.210 0.997    1.027    1.000          1.132 1.012        -0.146

HWY Calculations
  Motor kW       Engine kW     Fuel Efficiency     HC      CO     Nox 0-60MPH Max accel(ft/s2)      wt     grade     Rating
     15             100          #VALUE!         #DIV/0! #DIV/0! #DIV/0! #DIV/0! #DIV/0!          #DIV/0! #DIV/0!   #VALUE!
     15             110               0             0       0      0      1.018   0.952            1.154 0.990       -3.922
     15             120               0             0       0      0      1.020   0.956            1.151 0.991       -3.923
     15             130          #VALUE!          1.031   1.154 1.013     1.011   0.979            1.148 0.996      #VALUE!
     15             140             1.032         1.038   0.876 1.112     1.022   1.007            1.146 1.000       0.281
     15             150             1.033         0.979   0.799 1.040     1.035   1.007            1.143 1.000       0.341
     15             160             1.034         1.013   0.987 1.006     1.036   1.000            1.141 1.007       0.281
     15             170             1.028         1.017   1.037 0.980     1.038   1.000            1.138 1.010       0.241
     15             180             1.037         1.026   0.900 1.021     1.013   1.000            1.136 1.016       0.342
     15             190             1.031         1.026   0.978 0.989     1.013   1.000            1.134 1.019       0.294
     15             200             1.032         0.987   1.061 0.911     1.027   1.000            1.132 1.012       0.289




                                                             41